System for indicating the values of components of an electromotive force



sept. 5, 1939.

SYSTEM FOR INDICATING THE VALUES OF COMP ONENTS 0F AN ELIECTROMOTIVE FORCE Filed June 26, 1937 Y" AAnAnAlAAA "lvvvvvvvvv un un.

lvvvvlvvvvvv Patented Sept.' 5, 1939 UNITED STATES PATENT ori-'ICE SYSTEM FOB INDICATING THE VALUES 0F COMPONENTS FORCE4 AN\ ELECTBOMOTIVE* Application June 26, 1937, Serial No. 150,464 In Germany June 26, 1936 8 Claims.

My invention relates to an alternating-current compensator with an automatic balancing device.

An alternating-current compensator has been already proposed in which the two components of the voltage to be indicated are directly represented by the deection of two dynamometers whose eld windings are traversed by currents which are 90 out Aof phase and are taken from 0 that alternating-current source which also supplies the voltage to be indicated. The moving coils of both dynamometers are connected in series with the alternating voltage to be indicated. This known arrangement has the dissystems must be supplied by the testing circuit. Even in the caseof supporting the rotating systems as free of friction as possible, still a fraction of the measuring. voltage although low is not 0 compensated for and this fraction is the greater,

with even a very small supply ofA energy drawn from the'testing circuit. The use of the dynamometers for theV direct recording of the com- J pensated values cannot, therefore, be .taken by any means into consideration.

'I'he above-mentioned drawbacks of the known arrangement may be removed according to the invention if instead of the dynamometers, ini duction voltage regulators designed in the form of double coil instruments are employed, one coil of which (compensating coil) supplies thecompensating voltage, whereas the -second coil (directional coil) is influenced by the output current l of an amplifier whose input lies in the compensating circuit. With this arrangement it is possible to use an amplifier without this amplier having tomet with any special requirements as to the coincidence of phases, invariability-of .the

i power amplification ratio etc. and to completely J relieve the coils supplying --thecompensating voltage from the supply of mechanical adjusting energy. Consequently, the compensator accord.- ing to the invention'may also be readily employed i -for very low voltages. such as 0.01 volt, and further the rotatable part of the two compensating transformers may also be mechanically loaded so that'the 'corresponding position may, for in,

stance, vbe recorded withvthe aid of the usual i' reco` rding' u devices.

advantage that the energy for adjusting the' (Gl. P11-95) In the accompanying drawing is shown an vembodiment of my invention in diagrammatic form.-

Fig. l shows a wiring diagram, whereas Fig. 2 represents a vectordiagram showing the electrical processes within a compensator.

K1 and K1" designate two iron bodies in whose grooves are arranged exciting windings Sr' and Sr" respectively. Concentrically within the central circular recesses of the iron bodies are disl0 posed two cylindrical iron bodies Kz and K2" and within each o'f'the annular gaps formed, by the inner and outer iron vbodies is rotatably y mounted a double coil Si", Sz' and Si" and Sz" respectively. Each of these double coils is pro- 15 vided with an indicating element A which may represent for the'present purpose any indicating means including a recording hand of any approved construction. The exciting windings Sr' and Sr are, connected to but electrically sepa- 20 rated from the supply circuit U by separating transformers T and T", vfrom which circuit also the object to be tested is supplied with energy. In one exciting circuit is inserted a self-inductance L and in the other an ohmic resistance R 25 and a capacitor C are connected in parallel relation. These elements are so rated that the exciting currents of the two systems Aare practically 90 out of phase. Si and Si" designate the com- 'I pensating coils -supplying the 4compensating 30 voltages and feeding two iixed resistances Rx' and Rx" with energy through transformers Tx and Tx", the compensating voltages Uk' and UK" being tapped off from the Afixed resistances Rx' and Rx". To each of the circuits including 35 the two resistances Rx' and Rx" is furthermore allotted a parallel system comprising an ohmic resistance Rv' and Rv" and a capacitor Cv' and Cv" respectively so as to bring the compensating voltages Ux' and UK" to a value corresponding 40 to the purpose under consideration, in other words to adjust at will the .indicating range of the compensator. 'I'he other two moving coils S2' and S2 are connected in series 'in the output portional to the angles of deflection a and a". These voltages create through the transformers Tx and Tx proportional currents Jx' and JK" in both circuits TK', Rx', and Tx", Rx" respectively. These currents in turn produce in the resistances Rx and RK" voltage drops Ux' and UK proportional to the currents. These voltage drops serve to compensate the test voltage Ux. It is self-evident that the voltage at the input circuit of the amplifier will be zero, if a complete compensation is brought about. As long as this is not the case the still existing` differential voltage U0 acts on the amplifier so that the coils Sz andSz" are traversed by a current. Depending upon which of the two components is not yet completely compensated for, either coil S2' or S2, possibly both, will exert a torque so as to bring about a complete balance. By a correspending selection of the power amplification ratio a practically complete compensation may be brought abouteven in the case of considerable frictional resistances of the double moving coil. As to the above-described operation the capacitor CA has no importance at all. However, it is necessary, since through the output circuit of the amplifier both directional coils Sa' and S2" are so connected that they may inuence each other.

` S2" result from the equations 'Ihis undesirable reaction may be counterac d by Acorrespondingly rating the capacitor CA, i.y e., the capacitor is modified until with energized field windings SF and SF", but with deenergized amplifier, both double coils ,come to rest in a desired relative position.

In Fig. 2 is shown the vector diagram of the above-described embodiment of my invention. I to IV designate the coordinate system. I and fr are the primary fields in the induction voltage regulators produced by the currents JF' and Jr". Owing to the hysteretic and eddy current losses caused in the iron bodies, the magnetic uxes are shifted backwards by the phase angles e' and e", i. e. in practice by about l/2 to 1. So long as the measuring arrangement is not yet balanced the input voltage U0 is applied to the amplier; the input voltage is a result ofthe geometrical diierence betweeny the voltage to be tested UX=1/UX'2+ UX and the standard Voltage and may be dissolved in the two components Uo'=UX'-UK' and U,o=Ux' '-Ux". In the special case shown in Fig. 2 the phases of the magnetic fluxes l and I" are so chosen that the `phase shifting angle (UoJA) =(Uo', l1") =(Uo"-, I :90?v

If p' and p designatethe phase angles between JA and I and JA and I the torques D', D" whichact on the moving coils Si', S2' and Si",

D'=con`st. I .JAcos rp' It'follows that D' corresponds to the real component U0 and D" to the imaginary component U0" referredI to the magnitude and direction. The directions oi rotation of S1 and S2' and S1" and S2" are so chosen that the voltages Ux" and Un" and the angles of deflection a" and a" are varied in accordance with the desired adjustment of compensation. In this case the corresponding torque D1 or Dz is proportional to the corresponding magnitude of Uo' and Uo, that is to say to the corresponding departure from the stateof compensation. Hunting of the recording member connected to the moving coils maybe prevented by a suicient, preferably magnetic at- 5 tenuation. Nevertheless, an adjusting time of about 0.5 second may be attained.

Instead of the artificial connection shown in the above-described embodiment for attaining exciting currents Jr' and JF" 90 out of phase also other suitable connections may be employed; particularly a rotating field phase advancer may also be employed for this purpose. If these exciting currents Jr' and Jp are sinusoidal then the fundamental waves of the currents and voltages effective in the measuring arrangement are utilized for the measurement, whereas the harmonic vibrations are not taken into consideration. If a sinusoidal variation of the exciting Y currents cannot be taken as basis then the selectivity of the fundamental waves desired, as a rule, in the case of alternating-current compensation measurements may be attained by connecting in front of the tube amplifier V a multiunit filter circuit which keeps away the har- 25 monic vibrations contained in the voltages UK' and UK" from the zero indicator formed of the moving coils vancl the tube amplifier. v

'Ihe test reading is not influenced by the voltage fluctuations of the power source U, since they 3( vary in the-same manner the measuring. voltage Ux and the compensating voltages UK and UK". However, Athe power amplification ratio of the amplifier V is also varied. But since a pure zero method is adopted only 'the magnitude of the 35 torques D and D" and, therefore, the adjusting time of the rotatable instrument parts is thereby influenced.

As already above mentioned the compensator according to the invention lends itself also to 4| the amplification of very low voltages or may be used to bring about a full-automatic recording of both components of the test voltage.

The construction of the compensator which is relatively simple may in cases in which the meas- 41 uring voltage Ux has a given invariable position of phase be still considerably simplified, since there is only one direction of balance to be considered and only one double coil instrument need be provided. 5|

I claim as my invention:

1. In -an arrangement for indicating an alternating current voltage taken from an alternating current source, at least one electrodynamic indicating instrument having an exciting 5 winding connected to said source and a pair of movable coils fixed together and located in theeld of rsaid exciting winding, one serving as a compensating coil, the other as a directional coil and indicating means connected with said coils,

means for adjusting the phase relation of the exciting current with respect to the voltage, and an amplifier including in its input circuit thel indicated voltage and the output circuit of said compensating coil, andincluding said directional e coil in its outputcircuit.

2. In an arrangement for'indicating two outof-phase voltage components of an alternating current source, two electrodynamic indicating instruments, each having an exciting winding con- 7 ed with each pair of coils, means for adjusting the phaserelations of the currents in said exciting windings in accordance with the vphase relation of the components tobe indicated, and an amplier including in its input circuit the indicated voltage components and the output circuits oi said two compensating coils, and including-in its output circuit the two directional coils of said indicating instruments.

3. In an arrangement for indicating two outof-phase voltage components of an alternating current source, two electrodynamic indicating instruments, each having an exciting winding connected to said source and each having a pair of 'movable coils xed together and located in the eld of their appertaining exciting winding, one' coil serving as a compensating coil, the other as a directional coil and indicating means connected with each pair of coils, means for adjusting the phase relations of the currents in said exciting windings in accordance with the' phase relation of the components to be indicated, an ampliiier including in its input circuit the 'indicated voltage components and the output circuits of said two compensating coils, and including in its output circuit the two directional coils of said indieating instruments, and a capacitor for compensating for the reaction of said two directional coils upon one another.

4. In an arrangement for indicating two outof-phase voltage components of an alternating current source, two electrodynamic indicating instruments, each having an exciting winding connected to said source and each having a pair of movable coils fixed together and located in the iield of their appertaining exciting winding, one coil serving as a compensating coil, the other as a directional coil and indicating means connected with each pair of coils, means for adjusting the phase relations of the currents in said exciting windings in accordance with the phase relation of the components 'to be indicated, a compensating resistance in the outputcircuit of each compensating coil, and an amplier including in its input circut the indicated voltage components and the compensating resistances of said compensating coils and including in its output circuit the two directional coils of said indicating instruments.

5. In an arrangement, for indicating two out- Vof-phase voltage components of an alternating current source, two electrodynamic indicating instruments, each having an exciting winding ,connectedto said source and each having a pair of. movablev coils iixed together and located in the iield of their appertaining exciting winding, one

coil serving as a compensating coil, the other as aI directional coil and indicating means connected with each pair of coils, means for adjusting the phase relations of the currents in said exciting windings in accordance with the phase relation of the components to be indicated, a transformer for each compensating coil, having its primary winding in circuit with its appertaining coil and having a compensating resistance infits secondary circuit, and an ampliiler including in its input circuit the indicated voltage components and said compensating resistances ot said secondary transformer circuits, and including in its output circuit the two directional coils of said indicating instruments.

6. In an arrangement for indicating two outof-phase voltage components of an alternating current soruce, ltwoelectrodynamic indicating in struments, each havingan exciting winding'connected to said source and each having a pair of movable coils xed together vand located .in the field of their appertaining exciting winding, one coil serving as a compensating coil, the other fas a directional coil and indicating means connected With each pair of coils, means for adjusting the phase relations of the currents in said exciting windings infaccordance with the phase relation of the components to be indicated, a transformer for each compensating coil, having-its primary winding in circuit with its appertaining coil and having in its secondary circuit an ohmic resistance and a capacitor in mutual parallel connection and having a compensating Aresistance in series with said parallel connected elements, and an amplifier including in its input circuit the indicated voltage components and the compensating resistances of said secondary transformer circuits and including in its output circuit the two directional coils of said indicating instruments.

7. In an arrangement for indicating two outof-phase voltage components of an alternating current source, two transformers'each having its primary winding connected to said source, two electrodynamic indicating instruments, each having an exciting winding connected to the secondary winding of one of said transformers, and each having a pair of movable coils iixed tov gether and located in the field of their-appertaincircuit the two directional coils of said indicating instruments.

8. In an arrangement for measuring the real and imaginary components of an alternating voltage taken from an alternating current source, two electrodynamic measuring instruments, each having an exciting winding connected to said source and each having a pair of movable coils iixed together and located in the field of their appertaining exciting Winding; one coil serving as a compensating coil, the other as a directional coil, and indicating means connected with each pair of coils, means for shifting the currents in the two exciting windings out of phase, and an amplier including in its input circuit the measured voltage'components and the output circuits of said two compensating coils, and including in its output circuit the two directional coils of said indicating instruments.

WILHELM GEYGER. 

